An Investigation of Potential Sources of Nutraceuticals from the Niger Delta Areas, Nigeria for Attenuating Oxidative Stress

Abstract

Background: Diets rich in fruits, vegetables, and medicinal plants possess antioxidants potentially capable of mitigating cellular oxidative stress. This study investigated the antioxidant, anti-acetylcholinesterase (AChE), and total phenolic and flavonoids contents (TPC/TFC) of dietary sources traditionally used for memory enhancing in Niger Delta, Nigeria. Methods: Dacroydes edulis methanolic seed extract (DEMSE), Cola lepidota methanolic seed extract (CLMSE), Terminalia catappa methanolic seed extract (TeCMSE), Tricosanthes cucumerina methanolic seed extract (TrCMSE), Tetrapleura tetraptera methanolic seed extract (TTMSE), and defatted Moringa oleifera methanolic seed extract (DMOMSE); Dennettia tripetala methanolic fruit extract (DTMFE), Artocarpus communis methanolic fruit extract (ACMFE), Gnetum africana methanolic leaf extract (GAMLE), Musa paradisiaca methanolic stembark extract (MPMSE), and Mangifera indica methanolic stembark extract (MIMSE) were evaluated for free radical scavenging antioxidant ability using 2,2-Diphenyl-1-picrylhydrazyl (DPPH), reducing power capacity (reduction of ferric iron to ferrous iron), AChE inhibitory potential by Ellman assay, and then TPC/TFC contents determined by estimating milli-equivalents of Gallic acid and Quercetin per gram, respectively. Results: The radical scavenging percentages were as follows: MIMSE (58%), MPMSE (50%), TrCMSE (42%), GAMLE (40%), CLMSE (40%), DMOMSE (38%), and DEMFE (37%) relative to β-tocopherol (98%). The highest iron reducing (antioxidant) capacity was by TrCMSE (52%), MIMSE (40%) and GAMLE (38%). Extracts of MIMSE, TrCMSE, DTMFE, TTMSE, and CLMSE exhibited concentration-dependent AChE inhibitory activity (p < 0.05⁻0.001). At a concentration of 200 µg/mL, the AChE inhibitory activity and IC₅₀ (µg/mL) exhibited by the most potent extracts were: MIMSE (≈50%/111.9), TrCMSE (≈47%/201.2), DTMFE (≈32%/529.9), TTMSE (≈26%/495.4), and CLMSE (≈25%/438.4). The highest TPC were from MIMSE (156.2), TrCMSE (132.65), GAMLE (123.26), and CLMSE (119.63) in mg gallic acid equivalents/g, and for TFC were: MISME (87.35), GAMLE (73.26), ACMFE (69.54), CLMSE (68.35), and TCMSE2 (64.34) mg quercetin equivalents/gram. Conclusions: The results suggest that certain inedible and edible foodstuffs, most notably MIMSE, MPMSE, TrCMSE, GAMLE, and CLMSE may be beneficial to ameliorate the potentially damaging effects of redox stress.

Keywords: acetylcholinesterase inhibitor; antioxidants; memory enhancers; nutraceuticals.

Figure 1

DPPH radical scavenging activity of plant extracts. Plant antioxidant activity was measured via percentage inhibition of radical scavenging of DPPH. Results are expressed as means ± SEM for three separate experiments at each concentration. TeCMSE, Terminalia catappa methanolic seed extract; TTMSE, Tetrapleura tetraptera methanolic seed extract; TrCMSE, Tricosanthes cucumerina methanolic seed extract; DTMFE, Dennettia tripetala methanolic fruit extract; ACMFE, Artocarpus communis methanolic fruit extract; MPMSE, Musa parasidisiaca methanolic stem-bark extract; DMOMSE, Defatted Moringa oleifera methanolic seed extract; DEMSE, Dacroydes edulis methanolic seed extract; GAMLE, Gnetum africanum methanolic leaf extract; CLMSE, Cola lepidota methanolic seed extract; MIMSE, Mangifera indica methanolic stem-bark extract; Vit E, Vitamin E (β-Tocopherol). Results are expressed as means ± SEM for three separate experiments at each concentration. For marked significance from controls, a: p < 0.05, b: p < 0.01, c: p < 0.001.

Figure 2

Reducing capacity of plant extracts. Plant reducing power was assessed via the ability to reduce ferric (Fe³⁺) to ferrous (Fe²⁺) iron. The percentage increase of reductive capacity with increasing plant extract concentration was determined. Vitamin C was used as a positive control. Results are expressed as means ± SEM for three separate experiments at each concentration. TeCMSE, Terminalia catappa methanolic seed extract; TTMSE, Tetrapleura tetraptera methanolic seed extract; TrCMSE, Tricosanthes cucumerina methanolic seed extract; DTMFE, Dennettia tripetala methanolic fruit extract; ACMFE, Artocarpus communis methanolic fruit extract; MPMSE, Musa parasidisiaca methanolic stem-bark extract; DMOMSE, Defatted Moringa oleifera methanolic seed extract; DEMSE, Dacroydes edulis methanolic seed extract; GAMLE, Gnetum africanum methanolic leaf extract; CLMSE, Cola lepidota methanolic seed extract; MIMSE, Mangifera indica methanolic stem-bark extract. Results are expressed as means ± SEM for three separate experiments at each concentration. For marked significance from controls, a: p < 0.05, b: p < 0.01, c: p < 0.001.

Figure 3

AChE inhibitory activity of plant extracts. Plant inhibition of AChE was measured using a modified Ellman assay, with percentage inhibition of AChE calculated relative to eserine. Results are expressed as means ± SEM for three separate experiments at each concentration. MPMSE, Musa parasidisiaca methanolic stem-bark extract; DMOMSE, Defatted Moringa oleifera methanolic seed extract; DEMSE, Dacroydes edulis methanolic seed extract; GAMLE, Gnetum africanum methanolic leaf extract; CLMSE, Cola lepidota methanolic seed extract; MIMSE, Mangifera indica methanolic stem-bark extract; TeCMSE, Terminalia catappa methanolic seed extract; TTMSE, Tetrapleura tetraptera methanolic seed extract; TrCMSE, Tricosanthes cucumerina methanolic seed extract; DTMFE, Dennettia tripetala methanolic fruit extract; ACMFE, Artocarpus communis methanolic fruit extract. Results are expressed as means ± SEM for three separate experiments at each concentration. For marked significance from controls, a: p < 0.05, b: p < 0.01, c: p < 0.001.